Hydraulic accumulators with valves operated by the separating element are commercially available. In the technical reference published by Mannesmann Rexroth GmbH “Hydraulic Guide Volume 1”, on page 165, a bladder accumulator of this type is depicted and described. In the known bladder accumulator, the valve arrangement comprises a seat valve. A conical surface is formed on the end edge of a connecting sleeve facing the fluid space to provide a stationary valve seat. The conical surface interacts with a corresponding conical surface on the valve plate of the movable valve body. The valve is made similarly to the control valves conventionally used in valve-controlled internal combustion engines, i.e., the valve plate is located on a shaft guided in a valve guide for the valve lifting motion between the open position and closed position. The valve guide is installed in the connecting sleeve.
The disadvantage is the resulting high production costs due to the required cost for producing and machining of a host of individual parts as a result of this known valve design. To ensure proper operation of the valve arrangement, the valve guide installed in the connecting sleeve must be made carefully with respect to production tolerances for both alignment and fit. Moreover the corresponding machining of the conical surfaces which form the valve seat is necessary.
PCT/WO 00/31420 discloses a generic hydraulic accumulator with a separating element formed from metal bellows. Within the bellows is a compression spring which keeps the separating element in the pretensioned state. On its bottom, the bellows is provided with an end plate which interacts with a valve body accommodated in the fluid connecting sleeve of the housing of the known hydraulic accumulator and held under spring pretension. The valve body is made as a valve lifter and is larger in dimensions in its lengthwise alignment than in the transverse direction. Thus, the known valve body occupies considerable space in its direction of displacement in the connecting sleeve. The end of the valve body interacting with the end plate is made dome-like. In conjunction with the different diameters, grooves and recesses, beveled surfaces and the transverse hole on the other end of the valve body, a resulting complex geometry requires a complex and costly machining process in production. The complex geometrical structure of the closing body continues in the area of the fluid guide. As a result of the repeated deflection of the fluid flow, especially in the area of the incident flow of the medium into the fluid space, unfavorable flow behavior is implemented so that the known approach to hydraulic accumulators with sensitive membrane bladders is not suitable. U.S. Pat. No. 4,068,684 discloses a generic hydraulic accumulator. In the known approach, the spring-loaded valve body is a sleeve-shaped plug neck with a height measured in the direction of displacement of the valve body. The height is several times larger than its diameter. The valve body is formed on its side facing the separating element as a plate. The plate is flat. Its sleeve-like outside jacket has transverse holes diametrically opposite one another and connected to the fluid side of the hydraulic accumulator in the open position of the valve to carry fluid. The known valve body approach accordingly has a very large structure in the axial direction of the hydraulic accumulator. Due to the fluid-carrying transverse holes, the flow behavior cannot be choked and is consequently unfavorable in the area of inflow of the medium into the fluid space.